1. Field of the Invention
The present invention relates to a wrench extension with a socket-coupling system allowing quick attachment/detachment of a socket to/from an end of the wrench extension shaft.
2. Description of the Related Art
U.S. Pat. No. 5,531,140 discloses a coupling mechanism of socket wrench extension including an extension shaft (body). A first transverse passageway (opening) is defined in an end of the extension shaft and extends radially. A second transverse passageway (orifice) is defined in the extension shaft and adjacent to the end of the extension shaft. An axial passageway (axial bore) extends longitudinally from an end face of the end of the extension shaft and communicates with the first transverse passageway and the second transverse passageway. A transmission member (rod) is mounted in the axial passageway, and a spring is mounted in an inner end of the axial passageway with two ends of the spring respectively attached to an end wall defining the axial passageway and an end face of the transmission member. A stepped portion consisting of a cavity and a depression is formed on an outer end of the transmission member, and a cutout (aperture) is defined in an inner end of the transmission member. A push button (actuator) is slidingly received in the second transverse passageway with an end of the push button located outside the second transverse passageway for manual depression. The push button includes an inner hooked end (lateral projection) that extends through the cutout of the transmission member and an inclined face (tapered surface) above the hooked end. When the push button is in a normal undepressed position, the transmission member is biased outward by the spring such that a ball in the first transverse passageway is moved outward by the depression of the transmission member. When the push button is pushed, the inclined face of the push member urges the transmission member to move inward and compress the spring. The ball moves inward into the cavity of the transmission member, allowing insertion of the end of the extension shaft into a cavity (not shown) of a socket (not shown) or removal of the end of the extension shaft from the cavity of the socket. When the push button is released, the push button and the transmission member return to their original position. The protruded portion of the ball is engaged in a detent in the cavity of the socket, thereby coupling the socket to the end of the extension shaft.
Nevertheless, when the socket coupled to the end of the extension shaft is subject to an external force and thus moves in a direction away from the extension shaft, the ball is forced to move downward and causes inward movement of the transmission member. This is because no retaining means is provided for retaining the transmission member and the push button in place. Further, the stepped portion consisting of a cavity and a depression could not be used with all sockets due to tolerances. More specifically, the dimensions of the sockets manufactured by different manufacturers are slightly different from one another due to tolerances. As a result, the protruded portion of the ball may be either too large or too small for the detents of the cavities of the sockets. The socket would wobble relative to the end of the extension shaft when the user grips and applies an axial force to the socket. A reliable engagement between the end of the extension shaft and the socket regardless of the tolerance could not be obtained.
U.S. Pat. No. 4,962,682 discloses a wrench extension and socket coupler in which balls or a rod is used as the transmission member. In addition to the unreliable coupling resulting from tolerance in the detent of the cavity of the socket, the protruded height of the latch (also in the form of a ball) of the respective wrench extension may be different from each other, as the protruded height of the ball-like latch is affected by the tolerance of the balls. In some cases, the ball-like latch fails to protrude beyond the end of the wrench extension shaft.
An object of the present invention is to provide a wrench extension with a socket-coupling system allowing quick attachment/detachment of a socket to/from an end of the wrench extension and providing reliable coupling of the socket to the end of the wrench extension shaft.
A socket-coupling system in accordance with the present invention comprises:
a wrench extension shaft including an end, the end including an axial passageway extending along a longitudinal direction of the wrench extension shaft, the end further including a first transverse passageway extending in a direction transverse to the longitudinal direction of the wrench extension shaft, the first transverse passageway including an inner end communicated with the axial passageway and an outer end communicated with outside, the wrench extension shaft further including a second transverse passageway defined in an outer periphery thereof and extending in a direction transverse to the longitudinal direction of the wrench extension shaft, the second transverse passageway being communicated with the axial passageway and having an outer end communicated with outside;
a transmission member mounted in the axial passageway and slidable along the longitudinal direction of the wrench extension shaft, the transmission member including a recessed portion in an outer periphery thereof, the inner end of the transmission member including a sliding portion;
a latch partially received in the first transverse passageway and movable along an extending direction of the first transverse passageway, the latch being partially received in the recessed portion of the transmission member;
a push member mounted in the second transverse passageway and slidable along an extending direction of the second transverse passageway, the push member including an operative section having a sliding portion in sliding engagement with the sliding portion of the transmission member allowing mutual sliding movement between the sliding portion of the push member and the sliding portion of the transmission member; and
an elastic element mounted in the second transverse passageway for biasing the push member to an undepressed position;
one of the push member and the inner end of the transmission member including a pressing face;
wherein when the push member is pushed and a socket is coupled to the end of the wrench extension shaft, the latch is moved inward to allow passage of the socket, and the transmission member is moved by the latch along the longitudinal direction of the wrench extension shaft, and when the push member is released, the transmission member is moved along the longitudinal direction of the wrench extension shaft in response to movement of the push member under action of the elastic element until the recessed portion of the transmission member urges the latch to protrude into a detent of a cavity of the socket coupled to the end of the wrench extension shaft; and
wherein when the socket is subject to a force along the longitudinal direction of the wrench extension shaft for moving the socket away from the end of the wrench extension shaft, the pressing face on said one of the push member and the inner end of the transmission member being stopped by the other of the push member and the inner end of the transmission member, thereby preventing further movement of the transmission member along the longitudinal direction of the wrench extension shaft and reliably retaining a protruded portion of the latch in the detent of the socket.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.